Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada.
Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada.
Anal Chim Acta. 2019 Jun 20;1059:68-79. doi: 10.1016/j.aca.2019.02.008. Epub 2019 Feb 19.
Electroosmotic flow (EOF) in nanochannels as small as 85 nm and in small microchannels is systematically investigated by using the current-slope method. The effects of ion size, ion valence and pH of electrolyte solutions on the velocity of electroosmotic flow are experimentally studied. The results show that the large size of hydrated ions leads to higher EOF velocity in large nanochannels and microchannels, and, however, lower EOF velocity in small nanochannels with an overlapped electric double layer (EDL). Furthermore, the EOF velocity is proportional to the pH of the electrolyte solution and contrariwise proportional to the valence of counter-ions. It is also observed that the EOF velocity depends on the channel size in nanochannels, even without overlapped EDL. Several models of electric double layer (EDL) are proposed to explain the experimental results and provide an improved understanding of the effects of ion size, ion valence and pH of electrolyte solutions on the EOF velocity in nanochannels in terms of EDL structure.
通过电流斜率法系统地研究了小至 85nm 的纳米通道和小微型通道中的电渗流（EOF）。实验研究了离子大小、离子价态和电解质溶液 pH 值对电渗流速度的影响。结果表明，水合离子的大尺寸导致在大纳米通道和微通道中具有更高的 EOF 速度，而在重叠电双层（EDL）的小纳米通道中则具有更低的 EOF 速度。此外，EOF 速度与电解质溶液的 pH 值成正比，与抗衡离子的价数成反比。还观察到，EOF 速度取决于纳米通道中的通道尺寸，即使没有重叠的 EDL 也是如此。提出了几种电双层（EDL）模型来解释实验结果，并根据 EDL 结构提供了对离子大小、离子价态和电解质溶液 pH 值对纳米通道中 EOF 速度影响的更好理解。
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